Various types of sheet materials, such as plastic films, that have a layer of pressure sensitive adhesive on one surface are and have been in widespread use for the manufacture of signs for use in the identification art. The signs may consist of letters, numbers, symbols, or designs, etc., including combinations thereof, as required to convey the desired information. Signs made of pressure sensitive adhesive sheet materials can be divided into two broad categories: the sheet material is printed with the selected characters or the sheet material is configured in the shape of the selected information. The present invention relates to novel signmaking apparatus and methods for producing signs of the latter category from pressure sensitive adhesive sheet materials.
Adhesive sheet materials of the type involved in the present invention are releasably adhered to a liner which serves to cover and protect the adhesive layer during formation of a sign and until application of the sign to an object. Signs are made by cutting the selected characters in the sheet while mounted on the liner and then stripping the waste materials surrounding the legend, following which the sign is ready for application.
There are three categories of cutting systems, or methods, now used to cut characters from adhesive sheet materials in order to produce signs: (1) crush cutting, (2) knife or razor cutting, and (3) shear cutting.
The use of dies having raised cutting edges in the shape of characters or a set of characters for signs is an example of the crush cutting method of sign formation. See for example U.S. Pat. No. 3,465,627 (Vingneault, 1969) and U.S. Pat. 3,826,167 (Pelet et al., 1974). While die cutting can be used to produce signs with a legend having multiple characters, this is not generally practical because of the expense of producing a die for each legend. Therefore, die cutting most often is used to cut individual liner mounted characters, which are later combined or aligned to develop a selected legend for the sign. The dies can be brought into direct contact with the sheet material so that their cutting edges penetrate through the material to the liner upon actuation. Another type of die cutting involves indirect cutting of the sheet material and employs a flexible film over the adhesive sheet material which is to be cut; the die contacts the flexible film and the force is transmitted through the flexible film to cut the underlying sheet material even though the die does not directly contact or penetrate the sheet material. This technique is shown, for example, in U.S. Pat. No. 3,490,362 (Massari, 1970), U.S. Pat. No. 4,014,257 (Bettenhausen, 1977); U.S. Pat. No. 4,604,153 (Melbye, 1986); and U.S. Pat. No. 4,867,056 (Anderson et al., 1989).
U.S. Pat. Nos. 3,826,167, 4,014,257 and 4,867,056 cited above disclose machines for die cutting a sign from pressure sensitive sheet material that have legends formed of a plurality of characters. However, the machines of these patents utilize a separate die for each individual character (e.g. letter) in the sign, one character is die cut at a time, and thereafter a new die must be inserted in the machine to cut the next character. These patents demonstrate the impracticality of die cutting as a method for producing a sign having a plurality of characters from pressure sensitive adhesive sheet materials.
The more recent availability and development of microprocessor controlled X-Y plotters has provided an alternative means for producing signs from pressure sensitive adhesive sheet materials. Plotters for cutting adhesive sheet materials have been sold commercially by a number of companies, including ESAB Automation, Inc., Sign-Tronic USA Inc., Gerber Scientific and Sungraf Automated Systems. This type of machine is also disclosed in a number of patents, a representative listing of which is as follows:
U.S. Pat. No. 4,367,588 (Herbert, 1983), PA1 U.S. Pat. No. 4,467,525 (Logan et al., 1984), PA1 U.S. Pat. No. 4,512,839 (Gerber, 1985) PA1 U.S. Pat. No. 4,608,891 (Frisby et al., 1986), PA1 U.S. Pat. No. 4,732,069 (Wood et al., 1988), and PA1 U.S. Pat. No. 4,794,542 (Procter et al., 1988)
The plotter-type signmaking machines disclosed in the above patents use the knife or razor cutting technique to form signs from adhesive sheet materials. Thus, all of the above patents disclose a knife that cuts through the adhesive sheet material. The knife is supported in a vertical position on a carriage that is driven to travel in the cross machine, or Y-axis, direction. The sheet material generally is advanced in the machine direction, or X-axis, as it is being cut to form the characters of a sign. Also, the knife often is rotatable about a vertical, or .theta., axis as the sheet material is being cut. Thus, the prior art machines described in these patents employ a mechanism for moving the cutting knife in the cross machine direction and a second mechanism for driving the sheet material in the machine direction, together with a system for rotating the cutting knife about the .theta. axis, while cutting the sheet material in order to develop a sign of the selected configuration.
Other features of the above plotter-type signmaking machines include their use of a stationary anvil in association with the knife for cutting the sheet material. The anvil is a large stationary flat plate with an x-y mechanism in some machines and a rotating shaft in other machines. The prior art machines of the subject type also are generally designed for use with adhesive sheet material that has feed holes along its longitudinal edges and thus incorporate various types of sprocket drive mechanisms for advancing the sheet material through the machines.
The nature of the plotter type signmaking machines as taught by the prior art is such that these machines are generally large machines having various mechanical elements accurately supported in a substantial or heavy frame. For example, the components employed for feeding sheet material through the machines and accurately positioning the various mechanical elements relative to one another result in large bench or floor mounted machines. The cutting mechanisms and other components associated with this type of prior art signmaking machines also have imposed high power requirements. The plotter type signmaking machines taught by the patents listed above and the commercially available machines, therefore, are relatively expensive large machines that are suitable only for use at a fixed location. While some large companies can install such a machine at a fixed location in their plants, small and medium sized companies often must order signs from other companies that have the appropriate equipment and specialize in signmaking.